1. Field of the Disclosure
The disclosure relates to a hard mask composition for a lithography process. More specifically, the disclosure relates to an inorganic hard mask composition, which are useful in processes for etching fine patterns of a semiconductor device.
2. Related Technology
In order to prevent collapse of fine patterns of less than 100 nm, preferably less than 80 nm, a photoresist film is required to have a thickness of less than 100 nm. However, because the thickness of less than 100 nm is not enough to survive an etching process of a lower layer, a new hard mask is required, such as an amorphous carbon film.
Amorphous carbon that has the properties of organic materials can be thickly coated and shows a sufficient selectivity when the lower layer is etched. As a result, amorphous carbon can be used as a hard mask for etching the thick lower layer even when the photoresist film is thinly formed. This is also caused by that a silicon oxide nitride film that serves as a different hard mask can be deposited over the hard mask formed of amorphous carbon because amorphous carbon can survive at high temperatures of over 400° C.
FIGS. 1a through 1e are cross-sectional diagrams illustrating a conventional method for forming an underlying layer pattern of a semiconductor device using the above-described amorphous carbon film as a hard mask.
Referring to FIG. 1a, an underlying layer 12, an amorphous carbon film 14, a silicon oxide nitride film 16, an anti-reflective coating (hereinafter abbreviated to “ARC”) film 18 and a photoresist film 20 are sequentially formed on a semiconductor substrate 10. The amorphous carbon film 14 is typically formed at a thickness ranging from 100 nm to 800 nm by chemical vapor deposition equipment. The photoresist film 20 is typically formed at a thickness ranging from 40 nm to 200 nm.
Referring to FIG. 1b, the photoresist film 20 is selectively exposed and developed to form a pattern of the photoresist film 20.
Referring to FIG. 1c, a common etching process is performed to remove sequentially the lower ARC film 18 and the silicon oxide nitride film 16 with the pattern of the photoresist film 20 as an etching mask, thereby forming a pattern of the ARC film 18 and a pattern of the silicon oxide nitride film 16.
Referring to FIG. 1d, a common etching process is performed to remove the lower amorphous carbon film 14 with the pattern of the photoresist film 20, the pattern of the ARC film 18 and the pattern of the silicon oxide nitride film 16 which remain after the above etching process, thereby forming a pattern of the amorphous carbon film 14.
Referring to FIG. 1e, the lower underlying layer 12 is etched with the pattern of the amorphous carbon film 14 and the residual patterns after the above process to form a pattern of the underlying layer 12. Then, the residual patterns used as etching masks are removed by cleaning.
As noted above, the additional chemical vapor deposition equipment and a chemical vapor deposition gas have been conventionally required to deposit the amorphous carbon film 14 when the pattern of the underlying layer 12 is formed so that high cost is needed.
As a material for forming a hard mask used for etching fine patterns of semiconductor device, an organic polymer having a strong heat resistance can be used instead of the amorphous carbon. And an inorganic hard mask film having an excellent etching selectivity has been required which is formed over the organic hard mask film.